Maybe Postol should try a T-shirt or a bumper sticker, because the mug doesn't seem to be working. The Pentagon is all over him like medals on a four-star general.

"What they're trying to do is maneuver me into a situation where I can no longer talk," Postol says. "I intend to continue talking."

The subject is national missile defense, a complex system of radar-guided rockets designed to shoot incoming missiles out of the sky. The Bush administration wants to build the system to protect America from rogue states such as North Korea or Iraq.

"The technology to do so is within our grasp," Defense Secretary Donald H. Rumsfeld said in July, two days after one missile intercepted another in a test over the Pacific Ocean.

Postol claims that test was rigged. He says the Pentagon knows it can't field an effective missile shield and plans to build one anyway, concealing the system's ineffectiveness with unnecessary secrecy.

Lt. Col. Rick Lehner, the spokesman for the Ballistic Missile Defense Organization, says Postol's charges are unfounded and outdated because they involve a component of the system that has been replaced.

Yet the Pentagon has taken the trouble of sending security agents to Postol's office at the Massachusetts Institute of Technology, classifying his correspondence and demanding that the university confiscate documents from him and investigate his actions.

It seems mighty strange, this lone professor proclaiming that the Pentagon, the president of the United States and several giant defense contractors are all wrong and that he, Ted Postol, is right.

"They hate me for this. Of course they hate me," he says, brandishing one of his thick technical papers. "I'm shoving it in their face."

Colleagues and foes alike call Postol a brilliant, tenacious and egotistical man who never gives up. His adversaries often try to dismiss him as a crank or a charlatan, but they cannot deny one fact: Last time Ted Postol took on the Pentagon, he was right.

Postol is most famous for suggesting after the 1991 Gulf War that the Patriot air defense system might not have been the smashing success that the Army claimed--and then spending years proving it.

Working with George Lewis, another MIT professor, Postol analyzed news footage of more than 40 Patriot-Scud engagements frame-by-frame, about half of the Gulf War total. They concluded that not one Patriot appeared to have stopped a Scud from reaching the ground.

The Army and Raytheon, the company that built Patriot, responded with a barrage of criticism: News footage was too coarse-grained to show anything, the camera's shutter speed was too slow, the flashes didn't correspond with the exploding Patriots.

But soon, government investigators also began finding fault with Patriot. Both the General Accounting Office and Congressional Research Service found that Patriot's success rate was far lower than the 96% claimed by the Army.

In a new review, the Army revised its own estimate of Patriot effectiveness down to 60%. But almost everybody who was involved in the debate agrees the real number is closer to zero.

It appears Postol knew what he was talking about. Whether that's true this time is nearly impossible to tell, because he and his Pentagon adversaries argue more about each other's alleged misdeeds than the facts.

Postol's most recent fracas with the Pentagon started last year when he learned of a whistle-blower named Nira Schwartz who had sued her former employer, the defense contractor TRW. Schwartz charged TRW had faked test results performed for the national missile defense program.

Postol invited Schwartz to MIT, where she made her case to experts from the university and the Union of Concerned Scientists, an advocacy group opposed to the missile defense plan and dedicated to reducing nuclear arms.

"We actually were very impressed by her," says David Wright, a physicist with the group. "It looked like [her case] really held up."

Schwartz's central claim was that TRW's kill vehicle, designed to identify and destroy an incoming missile, could not tell the difference between a real warhead and a decoy. Both the company and the Ballistic Missile Defense Organization had declared a 1998 test of that capability a success.

The issue is important because any country technologically capable of launching an intercontinental ballistic missile could easily launch decoys. In an April 2000 study, a group of missile defense critics--including Postol--argued that simple decoys could render almost any missile defense system useless.

Lehner disputes that assertion. Furthermore, he says, TRW's kill vehicle has been dropped in favor of one built by Raytheon, which can distinguish warheads from decoys and "is going to get even better as time goes by."